It has been found desirable in discharging the contents of a railway car to invert the body of the vehicle. Such an operation is usually carried out with an unloading device wherein the car body is rotated about a longitudinal axis through substantially 180.degree. to effectively discharge granular or like materials from the car body of the hopper type. In such unloading operations, it is the practice to have the car being dumped remain coupled to adjacent upright railway vehicles.
Current designs of rotary couplers which rotate within the connecting yoke, are subject to torsional failure due to occasional jamming. Another drawback with rotary couplers has been their rapid wear rate, because of the lack of adequate bearing area at the swivel or rotary connection and vulnerability of the bearing surfaces to abrasive materials. Other problems facing rotary couplers are the need for special non-standard yokes and draft rigging, the need for inbuilt detent means to prevent unwanted rotation of the coupler head and in some cases, the need for a special configuration of car draft sill and draft gear pocket. Further problems include difficult assembly and disassembly and restricted lateral angling capability.
U.S. Pat. No. 2,869,736 discloses a rotary coupler in which a shank rotates about a drawbar. It contains a single boss for bearing and requires a special detent.
U.S. Pat. Nos. 2,973,104 and 2,973,105 disclose a rotary coupler arrangement in which the entire coupler is rotated within the yoke 180.degree. relative thereto.
U.S. Pat. No. 3,104,017 discloses a rotary coupler incorporating a cylindrical shank together with a slidable carrier which has a concave surface to fit the coupler shank and side positioned lugs on the carrier to prevent the shank from climbing off the carrier.
U.S. Pat. Nos. 3,157,290 and 3,157,291 disclose rotary couplers that utilize a special type of collar within the yoke to enable rotation of the entire coupler.
U.S. Pat. Nos. 3,220,562; 3,220,563; and 3,250,403 relate to a rotary coupler containing a means for detachably connecting the coupler shank to the head portion of a yoke to provide angular and/or rotational movements of the coupler relative to the yoke.
U.S. Pat. Nos. 3,589,529; 3,613,902; and 3,709,376 relate to other details concerning rotary couplers.
An object of the present invention is to provide a rotary coupler having a standard "F" coupler configuration that can be installed with the standard yoke, draft gear and striker arrangement.
Another object of the invention is to provide a rotary coupler having an improved bearing surface area particularly in the pull direction.
A further object of the invention is to provide a pivot for axial rotation of the coupler butt relative to the head and shank that is in line at all times.
Another object of the invention is to provide an enclosed pivot for axial rotation that can be permanently lubricated and protected from the entrance of abrasive material.
Yet another object of the invention is the provision of a rotary coupler that can be applied and removed in an identical manner to a standard "F" type coupler and require no special tools or equipment.
Another object of the invention is to provide a simple means of indicating for observation the amount of wear that has occured during service.
Still another object of the invention is to provide a rotary coupler with lateral and vertical angling capability identical to that of a standard "F" coupler.
A further object of the invention is to provide a rotary coupler that meets the latest AAR strength requirements.
A still further object of the invention is the provision of a coupler butt capable of rotating within the shank that does not require an inbuilt detent to hold the coupler head in normal running position.